How to Grow Phormium Plants

Guide to Growing New Zealand flax, Flax lily, and Mountain flax

Phormium are a tall genus of hardy perennials.

They range in height from 90 cm to over 3 metres (3 to 10 feet).

Most Phormium plants grown in gardens are half hardy perennials. They bloom in the summer.

Phormium tenax
Phormium tenax by Wallygrom.

They are mainly grown for their attractive leaves. These are sword shaped, and striped red, white, or yellow.

Some common names for members of Phormium plant genus include Mountain Flax, Flax Lily, and New Zealand Flax.

Commonly Grown Phormium Species Photographs and Plant Identification

Phormium tenax

Phormium tenax
Phormium tenax (New Zealand Flax / New Zealand Hemp), photograph by Forest and Kim Starr; CC.

Phormium colensoi

Phormium colensoi
Phormium colensoi (Lesser New Zealand Flax), picture by RuthP; CC.

Phormium Growing and Care Guide

Common Names: New Zealand flax, Flax lily, Mountain flax.
Life Cycle: Half hardy perennial.
Height: Up to 16 feet (5 m).
Native: New Zealand, Norfolk Island.
Growing Region: Zones 8 to 10.

Flowers: Summer.

Flower Details: Bright red. Curving. Tubular. Stalks to 16 feet (5

Foliage: Sword-shaped. Tough. Up to 10 feet (3 m) long. Green, but ornamental varieties may be pink or bronze. Can have striped edges and ribs of red, white, or yellow.

Sowing: Seeds of cultivars may not be true to type (usually revert to green or red). Cover seed. Can be sown in late winter but better results if sown in late autumn. Sow in plug trays under glass to increase germination rate in the spring.
Germination time: one to six months. Temperature: ~63°F (17°C). Supply weak potassium permanganate solution to prevent emerging seedlings from dying back.
Spacing depends on cultivars. Dwarfs can be spaced at about 12 inches (30 cm) while larger species are best spaced at about 40 inches (1 m).

Requirements and care: Full sunlight or partial shade. Sandy, fertile, moist soil. Regular watering during dry periods. Divide after three or four years to maintain vigor. Propagate: by dividing in the spring.

Family: Asphodelaceae.

Closely Related Species: Asphodelus.

Miscellaneous:The leaves have been traditionally used in New Zealand to produce fiber. Fairly deer resistant. Although the flowers are not ornamental they produce a lot of nectar and attract lots of birds and pollinating insects to the garden.

How to Grow New Zealand Flax and Mountain Flax

The seeds of New Zealand flax, Mountain Flax and other Phormium species should be sown outdoors in February. Simply cover the seeds once sown.

Alternatively, they can be started off indoors. Start growing them about 2 to 3 months in advance.

The germination time of Phormium plant seeds varies widely, ranging from one to six months. They should germinate fine at about 15 to 18 degrees centigrade (59 to 64°F).

Phormium plants should be spaced 30 cm (12 inches; small species), 50 cm (20 inches; medium sized species), or 90+ cm apart (over 3 feet; larger varieties).

They are quite versatile plants, and can be grown in both sunny and partially shaded areas.

The soil that Mountain Flax and other Phormium plants grow in should be moist, sandy and have a fertile composition.

Caring for Mountain Flax and other Phormium Plants

It is easy to look after Mountain flax, they require a moist soil so water regularly, and divide every three years or so to maintain vigorous growth.

If you require more Phormium plants, then propagate by division in the springtime.

Common Questions

How many members does the Phormium genus contain?

The Phormium genus contains only two species, which are commonly called New Zealand flax.

Do Phormium members make a good garden or landscaping plant?

Yes, Phormium plants are valued for their striking, sword-like leaves that come in a variety of colors, from deep green to bronze to variegated patterns. They are often used as focal points or in mass plantings in landscape design.

Which Phormium species are most frequently grown by gardeners?

Both species, Phormium tenax and Phormium cookianum, are grown, with P. tenax being the more common. There are many cultivars available, with varied leaf colors and patterns.

Are Phormium plants fragrant?

No, Phormium plants are not known for their fragrance.

What is the perfect location to grow Phormium?

Phormium plants prefer a sunny to partially shaded location with well-drained soil. They are tolerant of coastal conditions, including salt spray.

Is Phormium invasive in the USA, if so in which states?

P. tenax can be invasive in some areas, particularly in California, where it can crowd out native plants in natural habitats.

How do I remove Phormium plants from my garden?

Phormium can be tough to remove due to their large, fibrous root systems. Digging out the entire plant, including all roots, is necessary.

Summary

Phormium, commonly known as New Zealand Flax, is a genus in the Asphodelaceae family. This group includes perennial plants notable for their large, sword-like leaves and tall flower spikes.

These plants are ideally grown in full sun or partial shade and well-drained soil. The best time to plant Phormium is in the spring or early summer. With their architectural form and unique foliage, they make a striking addition to beds, borders, or as standalone specimens.

I hope that you enjoyed this guide on how to grow Phormium plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Aloe-vera Mountain Avens, Ixiolirion, and Asphodeline plants.